UNTII THE EARI Y nineteenth century, our knowledge of frankincense and myrrh and of their role in the economy of ancient South Arabia was wholly based on references in the Bible and GrecoRoman literature. Biblical writers made it clear that incense trade was one of the pillars of South Arabian economy, and to this general picture, classical authors added a wealth of information, as we shall see below. Unhappily their testimonies are not equally reliable and often conflict owing to the fact that their sources contained legendary material and were received secondor third-hand and these conflicts could not be rcsolved until new data had been brought to light. Important evidence bearing on the production and distribution of incense was discovered by a number of explorers and investigators in the nineteenth and early twentieth centuries. Although a nber of scholars touched on various aspects of this material, the first thorough-going evaluation of the ancient sources in the light of modern data was made by Adolf Grohmann, and his study, which appeared in two parts in 1922 and 1933,1 remains the standard work in this field. Since that time, new information has come to light which enables us to correct some earlier mistakes and to lay the groundwork -for a new synthesis. All problems are by no means solved, and some questions must remain unanswered until more evidence is forthcoming.